Juxtaglomerular apparatus is an apparatus consisting of a few cells of the glomerulus, distal tubule, and afferent and efferent arterioles It is involved in maintaining the glomerular filtration rate in the kidney. JGA is found to be located in a specialised region of a nephron, where the afferent arteriole and the distal convoluted tubule are in direct contact with each other. The juxtaglomerular apparatus consists of certain specialised cells of the afferent arteriole. These cells are known as juxtaglomerular cells and they contain the enzyme renin that can sense blood pressure. When there is a decrease in the glomerular filtration rate, the juxtaglomerular cells get activated and release renin which functions to converts the angiotensinogen in the blood into angiotensin I and further into angiotensin II. Angiotensin II is a powerful vasoconstrictor that can increase the glomerular filtration rate or glomerular blood pressure. Angiotensin II further stimulates the adrenal cortex of the adrenal gland to produce aldosterone which increases the rate of absorption of sodium ions and water from the distal convoluted tubule and the collecting duct. Later on, it leads to an increase in the blood pressure and glomerular filtration rate. This mechanism is known as the renin-angiotensin mechanism, ultimately leads to increased blood pressure. Juxtaglomerular apparatus plays an important role in the renin-angiotensin mechanism.